Heating drum



Jan. l8, 1955 G. c. HosAcK 2,700,094

HEATING DRUM Filed Feb. 6, 1951 2 sheets-sheet 1 i M g i Us N i1 1 N U11. l S l w l i3 l I li Q3 f I r o s, 9 izzzz: l :rr: il 1 o I o a f o l V v i' \N lago I Q a u l "I Q 1 i m r i N 1| i l. l I ll 1; V i I v 1 u' n' ,f l M INVENTOR. l ma/'Mmq 1 @www Jan. 18, 1955 G: Q HOSAK 2,700,094

HEATING DRUM Filed Feb. 6, 1.951

2 Sheets-Sheet 2 United States Patent O HEATING DRUM Gerald C. Hosack, Sanford, Fla., assignor to William S. Cloud, Wilmette, Ill.

Application February 6, 1951, Serial No. 209,692 6 Claims. (Cl. 219-19) For various purposes, it is desirable to have drums which are very uniformly and accuratelyheated and 111 which the temperature can be changed quickly. For example, in stretch-wrapping with Plloiilm, the Plloiilm should be heated to a optimum temperature. The optimum degree of heating is best reached by adjustmg the heating means during operation untll 1t gives the best results.

The use of oil-filled drums has been recognized as advantageous because of its simplicity and un1form heating action. During operation the oil is agltated enough so that the oil temperature is uniform and hence keeps the drum temperature uniform at all points on the surface of the drum. Oil-filled drums have been subJect, however, to the disadvantage that the temperature cannot be changed very quickly when desired.

According to the present invention, a heatmg drum with the advantages of the oil iill is provlded 1n which the temperature can be changed more quickly than w1th conventional oil-lled drums. Furthermore, the temperature is more dependably regulated.

Additional objects and advantages of themventlon will be apparent from the following descrlptlon and from the drawings.

Designation of figures to cover each new inventive concept therein 11o matter how it may later be disguised by variations in form or additions of further improvements; and the appended claims are intended to accomplish this purpose by particularly pointing out the parts, improvements, or combinations in which the inventive concepts are found.

General description According to the present invention, the drum is made up of an annular casting 11 having an outer wall 12, an inner wall 13 and end walls 14. It is thus apparent that the annular casting 11 forms an annular chamber 16.

The annular casting 11 may be supported by end plates 17, each of which may have a stub shaft 18 extending therefrom for rotatably mounting the drum. The end plates 17 may be notched annularly to fit the inner corners of casting 11, and may be held in the inter-titting position by two or more tie rods 19. To allow for differential expansion with changing temperatures, a spring 21 may be provided on each tie rod 19, a suitable tension being applied by nut 22. The casting 11 is desirably formed of aluminum, while the tie rods 19 are more likely to be formed of steel.

The chamber 16 is lilled with oil which is heated with a plurality of heaters 23. These heaters extend into the chamber 16 through the opposite end walls 14 to which they are threaded by pipe threads or in some other leakproof manner. As seen in Figs. 2 and 3, the heaters 23 may be distributed uniformly around the drum periph- ICC` erally, being illustrated as inserted through each end wall 14.

The heaters are controlled by thermostats 26, of which there are preferably several, as seen in Fig. 2, spaced equally around the drum. As shown by the circuit diagram, these thermostats 26 are preferably connected in series, so that if any one of them reaches the desired cutoff temperature, it will interrupt the circuit and de-energize heaters 23. It will be understood that the thermostats will usually operate indirectly, interrupting a circuit for the solenoid coil of a switch, the contacts of which will interrupt the circuit for the heaters 23. To this end, slip rings 27, 28 and 29 may be provided. So that these may be separately indicated in the circuit diagram of Fig. 2, they have been shown in three different diameters, although in practice they would be of the same diameter, if of the cylindrical type shown. One or more brushes will of course be provided for each slip ring. The slip ring 28 may engage a brush which is connected to a service wire representing a source of supply of electric current. As will be seen in Fig. 2, slip ring 28 is connected to one end of the circuit through the thermostats 26, the other end of the circuit being connected to slip ring 27 which engages a brush leading to the solenoid coil of the heater switch. Slip ring 28 is also connected to one side of the heater circuit, in which the heaters are connected in parallel. The other side of the heater circuit is connected to the slip ring 29. lt may be noted that wires extend through the drum to connect the heaters at both ends of the drum in parallel.

A lamp 31 is preferably connected in parallel with each of the thermostats 26 so that the condition of each thermostat can be detected. When the thermostat operates its contacts, the adjacent lamp 31 will be illuminated. The lamp will not permit enough current to pass to maintain actuation of the solenoid of the heater switch, these lamps being mere pilot lights. Observation of the lamps permits determination of any inequality of the thermostats so that they may be equalized or synchronzed by replacement or adjustment.

The use of at least three, preferably four, thermostats 1s desirable so that when the drum is at rest, one of the thermostats will always be near the top. Although rotation of the drum agitates the oil enough to maintain a uniform temperature throughout the chamber 16, convection currents, when the drum is stationary, tend to make the top hotter than the bottom. Excessive temperature may cause the iilm heated by the drum to divide or become too tacky. If the iilm divides,.rethread ing the machine is necessary. If the film becomes too tacky, it may stick to surfaces of the machine and require cleaning. With four or more thermostats, one is always near the top of the drum and hence near the hottest part of the drum if the drum is stationary. Hence when the desired temperature is reached at one point, the heaters will be shut off, although a further warming up may be required after the drum starts rotating with consequent equalization of the temperatures by consequent agitation of the oil.

Expansion of oil To provide for unequal expansion of the chamber 16 and the oil within it upon changes of temperature, something in the nature of an expansion tank is desired. According to the form of the invention (illustrated in m co-pending application, Serial No. 203,050 entitled Turret-Type Stretch-Wrapping) the chamber 16 may be connected through one of the shafts 18 with a stationary expansion tank. According to a preferred form of the invention, expansion means within the drum is provided instead. This may be a cylinder and piston, or a sealed, incompletely filled tank with an axial connection always below the liquid level therein. A form is preferred, however, more certain not to develop excessive pressures. To this end, a pipe 33 connects the chamber 16 with a series of diaphragm-type expansion wafers or expansion chamber units 34. Each of the expansion chamber units 34 may expand or contract axially of the drum to receive or discharge oil. It will be understood that each face of each unit 34 is a flexible diaphragm, preferably metal, the units thus comprising bellows.

Theexpansion chamber `units 34 may be -movably supported within the drum in any desired manner. One or two of them may be adequately supported by a T-shaped iitting v36 threaded into one of the fend plates i7.. One or two might not provide adequate expansion space, 'however, 4,and so the remainder are 'supported vwith ythe help of movable spiders 37. Although ythese Vspiders may anke various forms, they are preferably .provided with rollers 38 for ease of movement. The 'rollers .3.8 may Albe .camied by blocks `or feet ,39, lto which tubes 41 maybe secured. Tubes 41 have a sliding tit with rods 42 which `may be rigid with .a central .hub 431. The spring aroimd each rod y42 Ytends to center the hub `143:, .thus :approximately centering the yexpansion chambers 34 within the .drum. The curvature `of. :the `inside wail .13 rof casting ,i2 keeps the blocks 39 reasonably `aligned in parallelism with the axis -of the drum. If desired, rod i2 and tube 4'1 may be .square in cross section in yorder to maintain .the :alignment of blocks .39.. Preferably .each spider 37 includes 3 -or4 -arms :carrying the Vrollers 38.

`A thermometer 46 is preferably provided for indicating Vthe temperature :ofthe drum. It may ibe of the bulb type, having a bulb in the chamber 16.

Because some hlm has a tendency to shrink when it is heated, it may be vdesirable .to provide :some means for restraining the film ,from shrinkage as it rmoves around the drum. `For example, rgrooved rims 48 .may be secured to the drum .at its zends and the tilm held Aalong Aits edges by belts pressing rthe ilm :into the grooves, preferably pinching :the iilm against the sides of the grooves. This pinching .action will naturally follow., if V-belts .and grooves are used, if they iit .as usual.

To assist intilling or draining ythe chamber 16 .and to assist in changing :a :heater .23, one'or more :plugs 51 may be provided. These plugs are vnot necessary, however, because Athe .combination of the diaphragm .and .the heaters 23 makes llingorreplacing a heater 23 without the use y.of a plug V51 quite simple. The `defective heater is turned to the top of the drum. .As it .is loosened, the =oil pressure will tend to spread .the expansion chamber units 34 so that the oil will zfall below ythe level vof the top heaters. lfnecessary .to this end, the expansion chambers may be stretched out manually. The hea-ter may :then be removed :and replaced. .Before inserting .the .new heater, any .oil Aspilled may also -be .replaced The expansion chambers may then .be pressed together manually until the air has been lexpelled-from around the loosened -hea-ter, after which the heater may be tightened. The 1air will bre expelled y.more completely if :the drum is up-endedfor lif the plug .51 is loosened, while positioned at the top of the drum, to let .air escape from :the-very ltop .of the drum.

:1. .A .heating drum including inner and -outer walls and .end walls forming a peripheral chamber vof substantially Athe axial length of the drum and narrow 2in a radial direction, a body of liquid substantially 4tillin-g said cha-mber, van :expansion chamber communicating with the peripheral .chamber -andcarried by the drum, said expansion chamber including Aa plurality of flexible diaphragm-type expansion .chamber units and means for movably supporting .some of said units within the drum, comprising a hub to which a unit is secured, -telescoping tube and -rod means secured at one end .to the hub, roller means secured to the other end of the tube and rod means, and spring means tending to center the -hub with respect to the inner wall of the drum, and means for controllably heating Vthe fl-iquid in said peripheral chamber.

2. A heating drum including -inner and outer walls and end Walls forming a Vperipheral chamber of substantially theaxia'l length 'of the drum vand narrow in a radial direction, a body lof liquid substantially til-ling -said chamber, an expansion chamber communicating with the peripheral chamber and carried within the drum, said expansion chamber including a plurality of iiexible diaphragm-type expansion chamber units, means for movably supporting some of said units within the drum, and means for controllably heating the body of liquid.

3. A heating drum including inner and outer walls and end walls forming a peripheral chamber of substantially the axial length of 'the drum and narrow in `'a .radial direction, a body of liquid substantially iillin'g said chamber, an expansion chamber communicating with the peripheralchamber, Vand means for .controllab'ly heating the liquid in said chamber, including heaters in heating relationship with the liquid in the chamber and at least three thermostats equally spaced peripherally around the chamber responsive to the temperature of the liquid in the chamber and connected together to .interrupt kthe heating if any one of the 'thermostats reaches "the vcut-oli itemperature.

4. A heating dr-um including inner and outer walls and end wal-ls forming la peripheral chamber of :substantially the axial length of the drum `and `narrow in a Aradial direction, 'a body of liquid substantially iillingisaid chamber, an expansion chamber communicating with the peripheral chamber and carried by the drum, `said expansion chamber including ya plurality of flexible diaphragmtype expansion chamber units, means for movably supporting some of said units within the drum, vand means for heating the liquid -in the peripheral chamber, comprising a heating unit threaded -in sealed relationship to an end-wall and extending therethrough into direct contact with the liquid within the chamber.

'5. A heating ldrum -for heating plastic film and the like, including a peripheral wall and vadditional 'wall means forming a chamber for liquid in contact with 'the peripheral wall, heaters in heating relationship with the liquid in said chamber and at least three ther-mostats Hequally spaced peripherally around the drum in .proximity yto the peripheral vwall and connected together to cause reduction of the heating if any one of the thermostats reaches the cut-oft temperature.

6. A heating drum including a peripheral wall, additional walls form-ing with 'theperipheral wall `a peripheral chamber for holding liquid incontact with the lperipheral wall, an expansion vchamber communicating with -said chamber and jointly sealed therewith, with liquid substantially completely lling all of the space lin saidlchambers, and a heater extending through a -wall of the peripheral chamber into direct contact with the liquid therein 'and removable therefrom, ysaid expansion chamber being adapted, upon loosening the heater, to receive suicient liquid to llower the liquid level below the heater when positioned lat the ltop of vthe drum.

References Cited in the iile of kthis Vpatent UNIT-ED STATES PATENTS 429,559 Carpenter June 3, 1890 695,041 Fues Mar. l1, 1902 751,527 Marr Feb. 9, 1904 963,942 Richardson July r12, 1910 1,151,203 Lofquist Aug. 24, '191-'5 1,672,036 Oltman June 5, l1928 1,754,826 Hitchcock Apr. 15, 1930 1,812,802 Price June 30, 1931 2,322,957 Sullivan Jan. v29, 1943 2,474,759 Schmitz June 28, 1949 2,483,275 'Gregor Sept. 27, 1949 2,552,360 Zichis May 8, 1951 

